Method of and apparatus for forming rifled bores in metal



L. E. BOYER.

METHOD O F AND APPARATUS FOR FORMING RIFLED BORES IN METAL.

APPLICATION FILED OCT. 31.1916.

Patented Jan. 13, 1920.

UNITED. PATENT OFFICE.

LEWIS E. BOYER, 0F

EASTON; PENNSYLVANIA, ASSIGNOR TO INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION 0F NEWJERSEY.

METHon or AND APPARATUS ron FORMING RIF/LED Bones 1N METAL.

Specification of Letters Patent. Patented Jan, 13, 1920,

Application led October 31, Serial No. 128,647.

To all whom it may concern: Be 1t known that I, Lewis E. BOYER, a citizen of the United States, resldmg at Easton, 1n the county of Northampton and State. of Pennsylvania, have invented a certain new andl useful Improvement in the Methods of and Apparatus for Forming Riiied Bores in Metal, of which the following is a. specifica-tion.

This invention relates to an improved method 'of and apparatus for imparting a spiral. or rifled conformation to the walls of bores in metal or articles formed of metal.

In constructing such articles as rock drill pistons, for instance, which have an internal rifled bore arranged, in use, to engage a rifle bar, for rotation purposes, it has heretofore beeirtnecessary to bore out acomparatively large'portion of the center of the piston, to screw-thread the interior of this cavity and then insert therein a tubular nut the interior surface of which hasbeen previously rifled. The en'iployment of this method has been compulsory owing to the fact that it has been impossible to economically rifle the wall of a. 'bore which is open at but one end, or which, being open at both ends, has an opening at only one end of a dia-meter equal to or greater than that of the bore. Pistons produced with this construction have been uniformly weak and subject to breakage owing to the loss of metal sustained, and the frequent loosening of the rifle nut in use has been an additional serious disadvantage. l

The object of the present. invention is to eliminate the use of a rifle nut or other intermediate means and their accompanying evils by applying the ritled conformation of vthe inner bore of the piston directly to the Wall of the bore itself by forging, whereby the bore may be rified more perfectly and more expeditiously than by previously known methods, resulting in a piston structure which will be more efficient in operationv and possessed of increased strength and durability.

In the accompanying drawings I have illustrated an apparatus for carrying out my improved method, in which- Figures 1, 2 and 3 show the successive steps in the cycle of operations incident to the execution of the process,

Figs, 4: and 5, respectively, side and end 'following manner.

views of a rock drill piston blank prepar- -atory to being treated by the present method, and

Figs. 6 and 7, side and end views, respectively, of the piston blank subsequent to its treatment, provided with a rifled interior bore. A'

I have here shown my method as carried out` in connection with a heading machine the body 1 of which supports a pair of article holding dies or jaws 2 and 3, the jaw 2 being stationary and the jaw 3 movable. Coacting with the jaws 2 and 3 is a plunger 4 which has a reciprocatory movement, carrying athead block 5 in which is mounted a cylindrical punch holder 6. In this holder 6 is keyed or otherwise suitably secured a punch or former- 7 which acts as a rifling member, provided with spiral flutes 8 and. grooves 9. The holder 6 is revolubly mounted in the head block 5, being provided for this purpose with a circumferential fiange 10the opposite sides of which bear against balls 11 so that the. rifiing member 7 is at all times freely revoluble.

The above described apparatus is utilized to carry out my improved method in the The piston blank or other article 12 to bel treated is first provided with a preliminary cylindrical bore 13 of the desired length but of a diameter .preferably slightly less than that finally desired. The article 12 is then heated to the required forging temperature and placed between the jaws 2 and 3, this step being illustrated in Fig. l. The machine is then operated to close the movable jaw 3 upon the stationary jaw 2 and article 12 -as shown in Fig. 2. vThe plunger l carrying the head block 5 and revoluble rifling member 7 is then advanced toward the article 12 as shown in Fig. l3, the rifling member 7 entering the bore 13 and traveling to the limit of its movement. The rifled member in passing into the bore 13 revolves freely and `as it is forced in the spiral flutes 8 each forges a corresponding spiral channel or groove in the wall of the bore 13, the metal displaced thereby contributing toward the formation of flutes therein corresponding to the grooves 9 in the rifled member. The plunger 4 and punch 7 are then retracted to the position shown in Fig. 2 and the jaws finally opened to the position at the commencement of the operation illustrated in 110 the preliminary heatn use of a riiled member, in the manner above Fig. 1, the whole operation.f above described being completed within the s ace of a fraction of a second. 'The rifle bore 14 produced by the herein described method is@ perfectly formed. and requires no further y treatment except cleaning -by a sand blast or other means. A

In forming a rifled bore by the employment of this method it is not always necessary to first provide the article with a preliminary bore, or when the article to be formation to a single-ended bore forming the interior of a metal article by forging which consists in forcing a rifling member thereinto but not beyond the same and withdrawing the riing' member therefrom through the same end by a quick reciprocatorv movement, whereby the contour of the wall of the bore formed in the article will correspond with that of the riflmg member.

v 2. The method of imparting a rifled conformation to the interior of a metal article which consists in forcing a freely revoluble riding member thereinto and wlthdrawing the same therefrom, whereby the contour of the Wall of the b ore formed inthe article will- 'correspond with that of the rifling member.

3. The method of imparting a rified conformation to a'single-ended bore forming the interior of a metal a'rticle by forging `which consists in providing the article with a preliminary bore, forcing a riding member into but notv beyond the said bore and withdrawing the, rifling member therefrom through the saine end by a quicli reciprocatory movement, whereby the contour of the wall of the bore will correspond with that of the rifiing member.

4. The method of imparting a rified conformation to the interior of a metal article which consists in providing the article with a preliminary cylindrical bore, forcing a freely revoluble riiing member thereinto and withdrawing` the same therefrom, whereby, the contour of the wall of the bore will correspond -with that of the rifling member. y A

5. The method of imparting a rifled conformation to the interior of a metal article Y the article and to withdraw the which consists in providing the article with a preliminary bore of a diameter less than that nally desired, forcing a freely revoluble riing member thereinto and withdrawing the same therefrom, whereby the con- Y tour of the wall of the bore will correspond with that of the riiing member. Y

6. The-method of imparting a rifled c011- formation to la single-ended bore forming the interior of a-metal article by forging the interior of 4a metal article by forging 8 5 which consists in providing the article with a preliminary bore, preparing the article for forging, forcing a rifling member into but not beyond the said bore and withdraw.-

ing the same therefromthrough the'same 90 end by a quick reciprocator movement, whereby the contour of the wa of the bore will correspond with that of the rifling member.`

8. The method of imparting a rifled conformation to the interior of a metal article which consists in providing the article with a preliminary bore of a diameter less thanfinally desired, heating the article, forcing a freely revoluble riling member into the 100 said bore and withdrawing the rifling member therefrom, whereby the contour of the wall of the bore will correspond with that of the rifiing member.

9. An apparatus for imparting arilied conu formation t0 the .wall of an end-inclosed bore in a metal article by forging comprising article supporting means and means to force a rifiing member into but not beyond ber through the same end by a qulck reciprocatory movement, the resultant contour of the interior corresponding with the rilin g member.

10. A11 apparatus for impartin Y a rilied 115 conformation to the wall of an en -inclosed bore in a metal article by forging comprising article supporting meansand means to force a freely revoluble riling member into but not 4beyond the article and to withdraw 120 the riiling member through the same end by a quick reciprocatory movement, the resultant contour of the interior corresponding with the riiing member.

11'. An apparatus for imparting a riled 125 conformation to a single-ended bore forming the interior of a metal article by forging comprising means for supporting the article to be riied and a riiing member arranged to be forced into but not beyond said article movement, whereby the-80 rifling meml 1 0 and withdrawn therefrom through the same end of the article by a quick reciprocatory movement, the resultant contour of the interior corresponding with the riiing member. 12. An apparatusfor imparting a riied .conformation to a single-ended bore formingthe interior of a metal article by forging comprising means for supporting the article to 4be riied and a freely revoluble rifiing member arranged to be forced in to but not beyond `said article and withdrawn therefrom by a quick reciprocatory movement, vthe resultant contour of the interidr corresponding with the rifling member.

13. An apparatus for imparting a rifled conformation to a single-ended bore forming the interior of a metal article by forging comprising article holding means, means forsupporting a riling member, one of said means being revoluble, the said rifling member being arranged to be forced into but not beyond the article and withdrawn therefrom through the same end of the article by a quick reciprocatory movement, the resultant contour ofthe interior corresponding with the riiing member. 111. An apparatus for imparting a rifled conformation to the interior of a metal article comprising article holding means, means for Supporting a rifling member, one of said means being freely revoluble, the said rifling member being arranged to be forced into but not beyond the article and,"

withdrawn therefrom. c

A15. An apparatus for imparting a rifled conformation to a single-ended bore forming the interior of a metal article by forglng comprising article supportingmeans, a

plunger, a rifling member mounted on said plunger and arranged to be forced into but not beyond` said article and withdrawn therefrom through the same end of the arl ticle by a quick reclprocatory movement, the resultant contour of the interior correspond-- ingwith the rifling member.'-

16. An apparatus for imparting a riflcd conformation to a single-ended bore form ing the interior of a metal article by forging comprising article supporting means a reciprocating plunger associated therewith and a rifling member revolubly mounted on said plunger Land arranged to be forced into but not beyond said article and Withdrawn therefrom through the same end of the article by a quick reciprocatory movement, the

resultant contour of the interior corresponding with the rifling member.

17. An apparatus for imparting a rifled conformation to a single-ended bore forming the interior of a metal article by forging comprising article holding jaws, a

plunger and a rifling member carried by plunger and arranged to be forced into but not beyond ysaid article and withdrawn therefrom by a quick `reciprocatory movement, the resultant conto'ur .of the interior corresponding with the rifling member.

19. An apparatus for impartinga rifled conformation to 'xa single-ended bore forming the interior of a metal article by forging comprising a pair of, article holding jaws, a reciprocating plunger coacting therewith, a head block on said plunger, a freely revoluble holdin in said holding member arranged to be forced into but not beyond the article to be rifled' as Athe plunger is `reciprocatedand tol be withdrawn therefrom by aquick reciprocatory movement, the resultant contour of the interior corresponding ythe rifling member.

member housed in said plunger and a r1 mg member secured In testimony whereof I have hereunto set m hand.

y. LEWIS EgBoYER.' 

